P. Eyerer

Structure and tensile behavior of irradiation-and peroxide-crosslinked polyethylenes

Abstract Three grades of polyethylene differing mainly in their molecular weight were irradiation and peroxide crosslinked. Their gel content, degree of swelling, melting temperature, degree of crystallinity, and tensile properties were determined. The irradiation and peroxide crosslinking of the same polymers makes it possible to properly compare the effects of the two crosslinking methods. Upon irradiation the competition between crosslinking and chain scission reactions determines the level of the critical dose required to form the first gel and the magnitude of maximum attainable gel content. Crosslinking causes trapping of entanglements which then contribute to the effective network density determined by solvent swelling. crystalline polyethylene enhances the degree of crystallinity and crystal perfection while subsequent crystallization from the melt is hindered by the presence of crosslinks. The homogeneity of the crosslinked network, or distribution of crosslinks, depends on the crosslinking metho...

Effect of powder particle morphology on the sintering behaviour of polymers

The sintering behaviour of several amorphous and semicrystalline polymeric powders was studied. The coalescence of particles of polystyrene, PMMA and polyethylene of various molecular weights was photographically followed. The coalescence of the amorphous materials was found to depend on the common parameters affecting sintering including particle size and polymer viscosity. However, unexpectedly fast sintering was observed for the crystalline polyethylenes. The dominating factor in their coalescence, unaccounted for by the Frankel expression, is the internal particle morphology which increases the total particle surface energy. The polyethylene particles were actually found to be aggregates of small nodules, less than 1μm in diameter, interconnected by a very fine fibrillar network. It is concluded that some semicrystalline high viscosity polymers, known to be unprocessable by common methods, do sinter due to their highly developed internal particle morphology.

Economic and ecological material index for end of life and design of electronic products

This paper presents a method to calculate economic and ecological indicators to evaluate waste regarding material recycling. As material recycling is still a preferred option for closing the loop of electric and electronic equipment (EEE), it is important to have an indicator that offers the feasibility to evaluate the benefits and burdens of different recycling routes according to the contained materials and elements. Depending on the description of the economic and ecological potential of waste, the requirements and calculation method will be discussed.This paper presents a method to calculate economic and ecological indicators to evaluate waste in regard to material recycling. As material recycling is still a preferred option for closing the loop of electric and electronic equipment (EEE) it is important to have an indicator which offers the feasibility to evaluate the benefits and burdens of different recycling routes according to the contained materials and elements. Depending on the description of the economic and ecological potential of waste the requirements and calculation method is discussed.

BIAXIAL DEFORMATION BEHAVIOR OF PET DEPENDENT ON TEMPERATURE AND STRAIN RATE

Due to its material properties, PET is a very interesting and challenging material for thermoforming applications. During the thermoforming process it may be subjected to high deformations at elevated temperatures. Plug assisted deformation of PET was executed with a servo-hydraulic testing machine utilizing a special clamping device. The effect of strain induced crystallization for bi-axial deformation was investigated at different temperatures and strain rates. The influence on morphology and crystallization was investigated by x-ray diffraction and scattering as well as DSC measurements. The process of crystallization was investigated for different processing parameters. Although still transparent, the stretched PET has changed to a semi-crystalline material with distinct WAXD patterns known from uni-axial deformation.

Nondestructive Testing of Carbon Fibre Reinforced Plastics (CFRP) by Thermal Wave Radiometry

Photothermal inspection /1/ of glass fibre reinforced plastics has been performed previously by BUSSE and EYERER /2/. INGLEHART et al. used mirage effect detection of thermal waves to investigate nondestructive testing of carbon fibre reinforced plastics (CFRP) /3/. TITTMANN et al. generated thermal waves by ultrasonics /4/. Preliminary results on photothermal inspection of CFRP have been published /5,6/. CFRP is well suited for thermal wave analysis since its black colour provides highly efficient deposition of optical energy, while the large thermal diffusivity allows for offsets that exceed significantly the sizes of the optical focus and of the infrared-detector spot.

Environmental indicators for ICT products - a practical approach based on four steps

Societal concerns on pollution, hazardous materials, global warming and sustainability provoke responses from society. Public policy or changes in consumer behavior are specific examples. For electrical and electronic equipment (EEE) the released EU directives such as the WEEE (directive on waste of electrical and electronic equipment) and RoHS (restriction of the use of certain hazardous substances in EEE) and future directives such as EuP (ecodesign of energy-using products) are already having and will have a significant impact on how products are designed, built, used and treated at their end of life. To bear this challenge, measurable and understandable criteria for assessing and demonstrating the environmental performance of products are needed. Key methodology for a holistic and reliable environmental evaluation of products is Life Cycle Assessment (LCA). This scientifically established approach leads to useful and reliable results regarding environmental evaluation of the entire life cycle of products. From the acquisition of raw materials, over the use of the products to the end of life management all life cycle stages are considered. Product characteristics (such as weight and materials used, energy consumption during use) and all relevant inputs and outputs (such as energy, raw materials, emissions) occurring throughout the entire life cycle are regarded. To improve products from an environmental point of view, eco-design recommendations for product designers need to be reliable and easy to handle. Environmental performance indicators based on technical product characteristics and based on LCA permits to efficiently ameliorate the environmental profile of a product. Efficiently, since only a fraction of information input is needed, this approach provides a tailored and simplified method using environmental performance indicators. This paper introduces a consistent methodology for the development of environmental performance indicators for information and communication technologies (ICT) products.

Oberflächentechnologien für Kunststoffbauteile

Ein wesentlicher Aspekt der modernen Produktion von Gebrauchsgutern ist die Konzentration der gewunschten Eigenschaften weg vom Volumen hin zur Oberflache. Wahrend das Volumen statische Eigenschaften und die Formgebung vorgibt, bestimmt die Oberflache Haptik, Farbe, Glanz, Abnutzungsverhalten, Barrierewirkung, elektrische Leitfahigkeit, Benetzung und viele andere Eigenschaften, die den Charakter der Gebrauchsguter nach ausen pragen. In einigen Fallen werden die Eigenschaften durch immer dunnere Schichtsysteme mit hoher Funktionalitat erreicht. Typische Beispiele dieser Entwicklung sind lackierte Kunststoffteile im Fahrzeugbau, kratzfeste reflexionsarme und pflegeleichte Kunststoffoptiken, hartstoffvergutete Werkzeuge und Bauteile oder Barriereschichten in der Lebensmittelverpackung.

Recycling of Thin Film Solar Cell Modules — LCA and ECO2 Case Study

Today, solar energy is seen as one of the auspicious renewable energy sources. At the beginning of solar cells history in the 1950th, solar cells were labeled as adverse due to their high energy payback time and low efficiency, therefore their application were limited to aeronautic and astronautic fields as well as to small applications such as pocket calculators. Recent developments resulted in the improvement of the energy efficiency of solar cell modules, as a result, the solar cell modules became more competitive to other renewable energy resources. In this paper the EU funded project SENSE is presented, which aim is to develop a recycling system for thin film solar cells. An accompanying LCA study shows the environmental impact of the considered solar cell systems

Kreislauffähigkeit von Werkstoffen

Das vom Bundesministerium fur Bildung und Forschung geforderte Entwicklungs- und Demonstrationszentrum “Kreislauffahigkeit neuer Werkstoffe” am Fraunhofer ICT befasst sich mit der Problematik der Kreislaufschlieβung von Kunststoffen und Verbunden aus dem Automobilbereich. Aufgabe des Zentrums ist die Entwicklung von Kreislauffuhrungskonzepten sowie die Untersuchung und Bewertung der Kreislauffahigkeit neuer Werkstoffe, Verbundwerkstoffe und Werkstoffverbunde in enger Zusammenarbeit mit Industrieunternehmen. Der Beitrag zeigt den aktuellen Stand der Kreislauffuhrung von Kunststoffen und Aluminium im Automobilbereich auf und stellt die Chancen und Hemmnisse der Kreislauffuhrung dar.

Prüfung von Kunststoffen und Bauteilen

Bei der Verarbeitung von Kunststoffen zu Bauteilen treten infolge der Scherbeanspruchungen in der Schmelze beim Fullen der Form Orientierungen im Werkstoff auf. Es handelt sich hierbei um eine raumliche Ausrichtung von Molekulketten, daraus gebildeten kristallinen Einheiten wie Kristallite, Lamellen, Spharolithe und Fibrillen, des Weiteren Fullstoffe wie Fasern sowie Materialinhomogenitaten wie Lunker und Crazes. Diese Orientierungen konnen reversibler oder irreversibler Natur sein und beeinflussen entscheidend die Werkstoff- und Bauteileigenschaften.